Method and apparatus for activation of CSI-RS measurements in ltm

Abstract

A method performed by a UE for activation of CSI- RS measurements in LTM is provided. The method receives a first CSI measurement configuration and a first CSI report configuration, where the first CSI measurement configuration includes a set of SSB beams for LTM. The method starts to measure the set of SSB beams upon receiving the first CSI measurement configuration. The method receives a second CSI measurement configuration, where the second CSI measurement configuration includes a set of CSI-RS beams for LTM, a CSI measurement configuration ID, and a condition. The method upon receiving a MAC CE indicating the CSI measurement configuration ID, starts to measure the set of CSI-RS beams associated with the indicated CSI measurement configuration ID. The method upon determining that the condition is met, starts to measure the set of CSI-RS beams associated with the condition.

Description

METHOD AND APPARATUS FOR ACTIVATION OF CSI-RS MEASUREMENTS IN LTM

[0001] The present disclosure is related to wireless communication and, more specifically, to a User Equipment (UE), Base Station (BS), and method for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM) in the wireless communication networks.

[0002] Various efforts have been made to improve different aspects of wireless communication for the cellular wireless communication systems, such as the 5thGeneration (5G) New Radio (NR), by improving data rate, latency, reliability, and mobility. The 5G NR system is designed to provide flexibility and configurability to optimize network services and types, accommodating various use cases, such as enhanced Mobile Broadband (eMBB), massive Machine-Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC). As the demand for radio access continues to grow, however, there exists a need for further improvements in the next-generation wireless communication systems, such as improvements in a beam management procedure.

[0003] The present disclosure is related to a UE, a BS, and a method for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM) in the wireless communication networks.

[0004] In a first aspect of the present disclosure, a UE for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM) is provided. The UE includes at least one processor and at least one non-transitory computer-readable medium that is coupled to the at least one processor and that stores one or more computer-executable instructions. The computer-executable instructions, when executed by the at least one processor, cause the UE to receive, from a base station (BS), a first CSI measurement configuration and a first CSI report configuration associated with the first CSI measurement configuration, where the first CSI measurement configuration includes a set of synchronization signal block (SSB) beams for LTM; start to measure the set of SSB beams upon receiving the first CSI measurement configuration; receive, from the BS, a second CSI measurement configuration, where the second CSI measurement configuration includes at least one set of CSI-RS beams for LTM, at least one CSI measurement configuration identifier (ID) associated with the at least one set of CSI-RS beams for LTM, and at least one condition associated with the at least one set of CSI-RS beams for LTM; in response to receiving, from the BS, a medium access control (MAC) control element (CE) indicating one of the at least one CSI measurement configuration ID, start to measure one of the at least one set of CSI-RS beams, where the one of the at least one set of CSI-RS beams is associated with the one of the at least one CSI measurement configuration ID; and in response to determining that one of the at least one condition is met, start to measure the one of the at least one set of CSI-RS beams, where the one of the at least one set of CSI-RS beams is associated with the one of the at least one condition.

[0005] In some implementations of the first aspect, the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to store the first CSI measurement configuration upon receiving the first CSI measurement configuration, and store the second CSI measurement configuration upon receiving the second CSI measurement configuration.

[0006] In some implementations of the first aspect, the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to receive, from the BS, a second CSI report configuration association with the second CSI measurement configuration, and transmit, to the BS, a report including a measurement result based on the second CSI report configuration after measuring the one of the at least one set of CSI-RS beams.

[0007] In a second aspect of the present disclosure, a method performed by a user equipment (UE) for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM) is provided. The method includes receiving, from a base station (BS), a first CSI measurement configuration and a first CSI report configuration associated with the first CSI measurement configuration, where the first CSI measurement configuration includes a set of synchronization signal block (SSB) beams for LTM; starting to measure the set of SSB beams upon receiving the first CSI measurement configuration; receiving, from the BS, a second CSI measurement configuration, where the second CSI measurement configuration includes at least one set of CSI-RS beams for LTM, at least one CSI measurement configuration identifier (ID) associated with the at least one set of CSI-RS beams for LTM, and at least one condition associated with the at least one set of CSI-RS beams for LTM; in response to receiving, from the BS, a medium access control (MAC) control element (CE) indicating one of the at least one CSI measurement configuration ID, starting to measure one of the at least one set of CSI-RS beams, where the one of the at least one set of CSI-RS beams is associated with the one of the at least one CSI measurement configuration ID; and in response to determining that one of the at least one condition is met, starting to measure the one of the at least one set of CSI-RS beams, where the one of the at least one set of CSI-RS beams is associated with the one of the at least one condition.

[0008] In a third aspect of the present application, a BS for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM) is provided. The BS includes at least one processor and at least one non-transitory computer-readable medium that is coupled to the at least one processor and that stores one or more computer-executable instructions. The computer-executable instructions, when executed by the at least one processor, cause the BS to transmit, to a user equipment (UE), a first CSI measurement configuration and a first CSI report configuration associated with the first CSI measurement configuration, where the first CSI measurement configuration includes a set of synchronization signal block (SSB) beams for LTM; and transmit, to the UE, a second CSI measurement configuration, where the second CSI measurement configuration includes at least one set of CSI-RS beams for LTM, at least one CSI measurement configuration identifier (ID) associated with the at least one set of CSI-RS beams for LTM, and at least one condition associated with the at least one set of CSI-RS beams for LTM, where the first CSI measurement configuration causes the UE to start to measure the set of SSB beams upon receiving the first CSI measurement configuration, and the second CSI measurement configuration causes the UE to in response to receiving, from the BS, a medium access control (MAC) control element (CE) indicating one of the at least one CSI measurement configuration ID, start to measure one of the at least one set of CSI-RS beams, where the one of the at least one set of CSI-RS beams is associated with the one of the at least one CSI measurement configuration ID; and in response to determining that one of the at least one condition is met, start to measure the one of the at least one set of CSI-RS beams, where the one of the at least one set of CSI-RS beams is associated with the one of the at least one condition.

[0009] Aspects of the present disclosure are best understood from the following detailed disclosure when read with the accompanying drawings. Various features are not drawn to scale. Dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

[0010] FIG. 1 is a flowchart illustrating a method / process performed by a UE for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM), according to an example implementation of the present disclosure.

[0011] FIG. 2 is a flowchart illustrating a method / process performed by a BS for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM), according to an example implementation of the present disclosure.

[0012] FIG. 3 is a block diagram illustrating a node for wireless communication, according to an example implementation of the present disclosure.

[0013] The following contains specific information related to implementations of the present disclosure. The drawings and their accompanying detailed disclosure are merely directed to implementations. However, the present disclosure is not limited to these implementations. Other variations and implementations of the present disclosure will be obvious to those skilled in the art.

[0014] Unless noted otherwise, like or corresponding elements among the drawings may be indicated by like or corresponding reference numerals. Moreover, the drawings and illustrations in the present disclosure are generally not to scale and are not intended to correspond to actual relative dimensions.

[0015] For the purposes of consistency and ease of understanding, like features may be identified (although, in some examples, not illustrated) by the same numerals in the drawings. However, the features in different implementations may be different in other respects and may not be narrowly confined to what is illustrated in the drawings.

[0016] References to “one implementation,” “an implementation,” “example implementation,” “various implementations,” “some implementations,” “implementations of the present application,” etc., may indicate that the implementation(s) of the present application so described may include a particular feature, structure, or characteristic, but not every possible implementation of the present application necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “In some implementations,” or “in an example implementation,” “an implementation,” do not necessarily refer to the same implementation, although they may. Moreover, any use of phrases like “implementations” in connection with “the present application” are never meant to characterize that all implementations of the present application must include the particular feature, structure, or characteristic, and should instead be understood to mean “at least some implementations of the present application” includes the stated particular feature, structure, or characteristic. The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the equivalent.

[0017] The expression “at least one of A, B and C” or “at least one of the following: A, B and C” means “only A, or only B, or only C, or any combination of A, B and C.” The terms “system” and “network” may be used interchangeably. The term “and / or” is only an association relationship for describing associated objects and represents that three relationships may exist such that A and / or B may indicate that A exists alone, A and B exist at the same time, or B exists alone. The character “ / ” generally represents that the associated objects are in an “or” relationship.

[0018] For the purposes of explanation and non-limitation, specific details, such as functional entities, techniques, protocols, and standards, are set forth for providing an understanding of the disclosed technology. In other examples, detailed disclosure of well-known methods, technologies, systems, and architectures are omitted so as not to obscure the present disclosure with unnecessary details.

[0019] Persons skilled in the art will immediately recognize that any network function(s) or algorithm(s) disclosed may be implemented by hardware, software, or a combination of software and hardware. Disclosed functions may correspond to modules which may be software, hardware, firmware, or any combination thereof.

[0020] A software implementation may include computer-executable instructions and / or Artificial Intelligence (AI) / Machine Learning (ML) module(s) stored on a computer-readable medium, such as memory or other type of storage devices. One or more microprocessors or general-purpose computers with communication processing capability may be programmed with corresponding computer-executable instructions and perform the disclosed network function(s), AI / ML module(s), or algorithm(s). The AI / ML module(s) may be implemented with a supervised learning approach, a semi-supervised learning approach, an unsupervised learning approach (e.g., Transductive approach and Inductive approach), a federated learning approach, or a reinforcement learning (RL) approach, but the present disclosure is not limited thereto. The computer-executable instructions associated with the AI module(s) and / or the ML module(s) may include but are not limited to, data management instructions (e.g., collection instructions, validation instructions…etc.), model monitoring and management instructions (e.g., NW KPIs monitoring, model input / output monitoring, model selection / switching / update / upload / download, model (de)activation, model identification, functionality selection…etc.), and / or pre-process input instructions.

[0021] The microprocessors or general-purpose computers may include Application-Specific Integrated Circuits (ASICs), programmable logic arrays, Central Processing Units (CPUs), Tensor Processing Units (TPUs), Graphics Processing Units (GPUs), General-purpose computing on GPUs (GPGPU, or less often GPGP), and / or one or more Digital Signal Processor (DSPs). Although some of the disclosed implementations are oriented to software installed and executing on computer hardware, alternative implementations implemented as firmware, as hardware, or as a combination of hardware and software are well within the scope of the present disclosure. The computer-readable media may include computer-storage media and communication media. Computer-storage media may include both volatile (and / or non-volatile media), and removable (and / or non-removable) media implemented in any method or technology for storage of information such as computer-readable instructions (e.g., computer-readable instructions related to AI module(s) and / or the ML module(s)), data structures, program modules or data.

[0022] The computer-readable medium may include, but is not limited to, Random Access Memory (RAM), Dynamic Random Access Memory (DRAM), High Bandwidth Memory (HBM), Magnetoresistive Random Access Memory (MRAM), Ferroelectric Random Access Memory (FRAM), Resistive Random Access Memory (RRAM), Read-Only Memory (ROM), Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), flash memory (or other memory technology), Compact Disc Read-Only Memory (CD-ROM) , Digital Versatile Disks (DVD) (or other optical disk storage), magnetic cassettes, magnetic tape, magnetic disk storage (or other magnetic storage devices), or any other equivalent medium capable of storing computer-readable instructions. Computer-storage media may not include a propagated data signal. Communication media may typically embody computer-readable instructions (e.g., computer-readable instructions related to AI module(s) and / or the ML module(s)), data structures, program modules, or other data in a modulated data signal, such as a carrier wave, or other transport mechanisms and include any information delivery media.

[0023] A radio communication network architecture such as a Long-Term Evolution (LTE) system, an LTE-Advanced (LTE-A) system, an LTE-Advanced Pro system, a 5G NR Radio Access Network (RAN), 5G-Advanced (5G-A) system, or an open radio access network (O-RAN) may typically include at least one base station (BS), at least one UE, and one or more optional network elements that provide connection within a network. The BS and one or more optional network elements enable the UE to access a radio network. Thus the UE may communicate with the network, such as a Core Network (CN), an Evolved Packet Core (EPC) network, an Evolved Universal Terrestrial RAN (E-UTRAN), a Next-Generation Core (NGC), a 5G Core (5GC), or an internet via a RAN established by one or more BSs and the network elements / functions.

[0024] A UE may include, but is not limited to, a mobile station, a mobile terminal or device, or a user communication radio terminal. The UE may be a portable radio equipment that includes, but is not limited to, a mobile phone, a tablet, a wearable device, a sensor, a vehicle, a virtual reality (VR) device, an augmented (AR) device, an Internet of Things (IoT) device, an unmanned aerial vehicle (UAV), or a Personal Digital Assistant (PDA) with wireless communication capability. The UE may be configured to receive and transmit signals over an air interface to one or more cells in a RAN. In some implementations, the UE may be an AI / ML-enabled device and / or an AI / ML capable device that is equipped with AI module(s) and / or ML module(s).

[0025] The BS may be configured to provide communication services according to at least a Radio Access Technology (RAT), such as Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile communications (GSM) that is often referred to as 2G, GSM Enhanced Data rates for GSM Evolution (EDGE) RAN (GERAN), General Packet Radio Service (GPRS), Universal Mobile Telecommunication System (UMTS) that is often referred to as 3G based on basic Wideband-Code Division Multiple Access (W-CDMA), High-Speed Packet Access (HSPA), LTE, LTE-A, evolved / enhanced LTE (eLTE) that is LTE connected to 5GC, NR (often referred to as 5G), 5G-A, and / or LTE-A Pro. However, the scope of the present disclosure is not limited to these protocols.

[0026] The BS may include, but is not limited to, a node B (NB) in the UMTS, an evolved node B (eNB) in LTE or LTE-A, a radio network controller (RNC) in UMTS, a BS controller (BSC) in the GSM / GERAN, a next-generation eNB (ng-eNB) in an Evolved Universal Terrestrial Radio Access (E-UTRA) BS in connection with 5GC, a next-generation Node B (gNB) in the 5G-RAN (or in the 5G Access Network (5G-AN)), or any other apparatus capable of controlling radio communication and managing radio resources within a cell. The BS may serve one or more UEs via a radio interface. In some implementations, the BS may be an AI / ML-enabled device and / or an AI / ML capable device that is equipped with AI module(s) and / or ML module(s).

[0027] The BS may be operable to provide radio coverage to a specific geographical area using multiple cells forming the RAN. The BS may support the operations of the cells. Each cell may be operable to provide services to at least one UE within its radio coverage.

[0028] Each cell (may often referred to as a serving cell) may provide services to one or more UEs within the cell’s radio coverage, such that each cell schedules the DL (and optionally UL resources) to at least one UE within its radio coverage for DL (and optionally UL packet transmissions from the UE). The BS may communicate with one or more UEs in the radio communication system via the cells.

[0029] A cell may allocate Sidelink (SL) resources for supporting Proximity Service (ProSe), LTE SL services, LTE / NR sidelink communication services, LTE / NR sidelink discovery services, and / or LTE / NR Vehicle-to-Everything (V2X) services. In addition, a cell may allocate DL and / or UL resources for supporting Multicast / Broadcast Service (MBS) services, Non-Terrestrial Networks (NTN) services, positioning services, power serving services and / or Network Energy Saving (NES) services. Each cell may have overlapped coverage areas with other cells.

[0030] In Multi-RAT Dual Connectivity (MR-DC) cases, the primary cell of a Master Cell Group (MCG) or a Secondary Cell Group (SCG) may be referred to as a Special Cell (SpCell). A Primary Cell (PCell) may include the SpCell of an MCG. A Primary SCG Cell (PSCell) may include the SpCell of an SCG. MCG may include a group of serving cells associated with the Master Node (MN), including the SpCell and optionally one or more Secondary Cells (SCells). An SCG may include a group of serving cells associated with the Secondary Node (SN), including the SpCell and optionally one or more SCells.

[0031] As discussed above, the frame structure for NR may support flexible configurations for accommodating various next generation (e.g., 5G) communication requirements, such as Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), and Ultra-Reliable and Low-Latency Communication (URLLC), while fulfilling high reliability, high data rate, and low latency requirements. The Orthogonal Frequency-Division Multiplexing (OFDM) technology in the 3GPP may serve as a baseline for an NR waveform. The scalable OFDM numerology, such as adaptive sub-carrier spacing, channel bandwidth, and Cyclic Prefix (CP), may also be used.

[0032] Two coding schemes may be considered for NR, specifically, Low-Density Parity-Check (LDPC) code and Polar Code. The coding scheme adaption may be configured based on channel conditions and / or service applications.

[0033] At least the DL transmission data, a guard period, and UL transmission data should be included in a transmission time interval (TTI) of a single NR frame. The respective portions of the DL transmission data, the guard period, and the UL transmission data should also be configurable based on, for example, the network dynamics of NR. SL resources may also be provided in an NR frame to support ProSe services or V2X services.

[0034] Any two or more than two of the following paragraphs, (sub)-bullets, points, actions, behaviors, terms, or claims described in the present disclosure may be combined logically, reasonably, and properly to form a specific method.

[0035] Any sentence, paragraph, (sub)-bullet, point, action, behaviors, terms, or claims described in the present disclosure may be implemented independently and separately to form a specific method.

[0036] Dependency, e.g., “based on”, “more specifically”, “preferably”, “in one embodiment”, “in some implementations”, etc., in the present disclosure is just one possible example which would not restrict the specific method.

[0037] In some implementations, all the designs / embodiment / implementations introduced within this disclosure are not limited to be applied for dealing with the problems discussed within this disclosure. For example, the described embodiments may be applied to solve other problems that exist in the RAN of wireless communication systems. In some implementations, all of the numbers listed within the designs / embodiment / implementations introduced within this disclosure are just examples and for illustration, for example, of how the described methods are executed.

[0038] The term “A and / or B” within the present disclosure means “A”, “B”, or “A and B”. The term “A and / or B and / or C” within the present disclosure means “A”, “B”, “C”, “A and B”, “A and C”, “B and C”, or “A and B and C”. The term “A / B” within the present disclosure means “A” or “B”.

[0039] Multiple public land mobile networks (PLMNs) may operate on the unlicensed spectrum. Multiple PLMNs may share the same unlicensed carrier. The PLMNs may be public or private. Public PLMNs may be, but are not limited to, the operators or virtual operators, which provide radio services to the public subscribers. Public PLMNs may own the licensed spectrum and support the radio access technology on the licensed spectrum as well. Private PLMNs may be, but are not limited to, the micro-operators, factories, or enterprises, which provide radio services to their private users (e.g., the employees or machines). In some implementations, public PLMNs may support more deployment scenarios (e.g., the carrier aggregation between the licensed band NR (PCell) and NR-U (SCell), the dual connectivity between the licensed band LTE (PCell) and NR-U (PSCell), the stand-alone NR-U, an NR cell with DL in the unlicensed band and UL in the licensed band, the dual connectivity between the licensed band NR (PCell) and NR-U (PSCell)). In some implementations, private PLMNs may mainly support, but are not limited to, the stand-alone unlicensed radio access technology (e.g., the stand-alone NR-U).

[0040] The terms “network (NW)”, “cell”, “camped cell”, “serving cell”, “base station”, “gNB”, “eNB”, and “ng-eNB” may be used interchangeably. In some implementations, some of these terms may refer to the same network entity.

[0041] The RAT may be, but is not limited to, NR, LTE, E-UTRA connected to 5GC, LTE connected to 5GC, E-UTRA connected to EPC, and LTE connected to EPC. The proposed mechanism in the present disclosure may be applied to UEs in public networks or in private networks (e.g., non-public network (NPN), standalone NPN (SNPN), public network integrated-NPN (PNI-NPN)).

[0042] The proposed mechanism in the present disclosure may be used for the licensed frequency and / or the unlicensed frequency. In addition, the proposed mechanism of conditional configuration selection may be applied for the cases that a UE experiences a radio link failure when configured with conditional configurations.

[0043] The system information (SI) may refer to the MIB, SIB1, and other SI. The minimum SI may include the MIB and SIB1. Other SI may refer to SIB3, SIB4, SIB5, and other SIB(s).

[0044] The dedicated signaling may refer to, but is not limited to, the RRC message(s). For example, the RRC (Connection) Setup Request message, RRC (Connection) Setup message, RRC (Connection) Setup Complete message, RRC (Connection) Reconfiguration message, RRC Connection Reconfiguration message including the mobility control information, RRC Connection Reconfiguration message without the mobility control information inside, RRC Reconfiguration message including the configuration with sync, RRC Reconfiguration message without the configuration with sync inside, RRC (Connection) Reconfiguration Complete message, RRC (Connection) Resume Request message, RRC (Connection) Resume message, RRC (Connection) Resume Complete message, RRC (Connection) Reestablishment Request message, RRC (Connection) Reestablishment message, RRC (Connection) Reestablishment Complete message, RRC (Connection) Reject message, RRC (Connection) Release message, RRC System Information Request message, UE Assistance Information message, UE Capability Enquiry message, and UE Capability Information message.

[0045] The proposed implementations described in the present disclosure may be applied to the RRC_CONNECTED UE, RRC_INACTIVE UE, and RRC_IDLE UE.

[0046] The source cell may include a suitable cell or an acceptable cell.

[0047] A suitable cell may be a cell on which a UE may camp. The UE may consider a cell as suitable if the following conditions (1) and (2) are fulfilled. (1) The cell is part of either the selected PLMN or the registered PLMN or PLMN of the Equivalent PLMN list, and (2) the cell criteria of the cell are fulfilled. Furthermore, according to the latest information provided by NAS, the suitable cell may not be barred. The suitable cell may be part of at least one TA that is not part of the list of “Forbidden Tracking Areas”, which belongs to a PLMN that fulfils the condition (1).

[0048] An acceptable cell may be a cell on which the UE may camp to obtain limited service (e.g., originate emergency calls, and receive ETWS and CMAS notifications). Such a cell may fulfil the following requirements, which is the minimum set of requirements to initiate an emergency call and to receive ETWS and CMAS notification in an NR network: (1) the cell is not barred, and / or (2) the cell selection criteria are fulfilled.

[0049] Examples of some selected terms in the present disclosure are provided as follows.

[0050] Primary Cell (PCell): The MCG cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure.

[0051] Primary SCG Cell (PSCell): For dual connectivity operation, the SCG cell in which the UE performs the random access when performing the Reconfiguration with Sync procedure.

[0052] Serving Cell: For a UE in the RRC_CONNECTED not configured with CA / DC, there may be only one serving cell including the primary cell. For a UE in the RRC_CONNECTED configured with CA / DC, the term “serving cells” may be used to denote the set of cells including the Special Cell(s) and all secondary cells.

[0053] Secondary Cell (SCell): For a UE configured with CA, a cell that provides additional radio resources on top of the Special Cell.

[0054] Special Cell (SpCell): For Dual Connectivity operation, the term “Special Cell” may refer to the PCell of the MCG or the PSCell of the SCG, otherwise the term “Special Cell” may refer to the PCell.

[0055] Master Cell Group: In MR-DC, a group of serving cells associated with the Master Node, including the SpCell (or PCell) and optionally one or more SCells.

[0056] Master node: In MR-DC, the radio access node that provides the control plane connection to the core network. The master node may include a Master eNB (e.g., in EN-DC), a Master ng-eNB (e.g., in NGEN-DC) or a Master gNB (e.g., in NR-DC and NE-DC).

[0057] Secondary Cell Group: In MR-DC, a group of serving cells associated with the Secondary Node, including the SpCell (or PSCell) and optionally one or more SCells.

[0058] Secondary node: In MR-DC, the radio access node, with no control plane connection to the core network, providing additional resources to the UE. The secondary node may include an en-gNB (e.g., in EN-DC), a Secondary ng-eNB (e.g., in NE-DC) or a Secondary gNB (e.g., in NR-DC and NGEN-DC).

[0059] The serving cell may include a PCell, SCell, or PSCell.

[0060] The term “source node” may be referred to the node from which the UE receives a CSC, and it may be interpreted as a source MN, a source SN, a source PCell, a source PSCell, or a source gNB.

[0061] The term “source cell” may be the cell from which the UE receives a CSC, and it may be interpreted as a source PCell or a source PSCell.

[0062] The term “candidate node” may be referred to the node that is associated with the LTM candidate configuration stored by the UE, and it may be interpreted as a candidate MN, a candidate SN, a candidate PCell, a candidate PSCell, or a candidate gNB.

[0063] The term “candidate cell” may be referred to the cell which is associated with the LTM candidate configuration stored by the UE, and it may be interpreted as a candidate PCell or a candidate PSCell.

[0064] The term “target node” may be referred to the node which is associated with the LTM candidate configuration ID in the CSC received by the UE, and it may be interpreted as a target MN, a target SN, a target PCell, a target PSCell, or a target gNB.

[0065] The term “target cell” may be referred to the cell which is associated with the LTM candidate configuration ID in the CSC received by the UE, and it may be interpreted as a target PCell or a target PSCell.

[0066] In some implementations, the system information may be associated with the serving cell. In some implementations, the system information may be associated with the candidate / target cell.

[0067] In the wireless cellular network, mobile devices (e.g., UEs) may move from the coverage area of one cell to another cell. To avoid the connection interruption and ensure the service continuity, the handover procedure may be applied for the mobile devices when the handover procedure is triggered under certain conditions (e.g., when the signal quality of the source cell becomes poorer / lower than a threshold for a period).

[0068] The handover procedure may be triggered by Layer 3 (L3) measurements and may be completed by Radio Resource Control (RRC) signaling triggered Reconfiguration with Synchronization for change of the Primary Cell (PCell) and Primary Secondary Cell (PSCell) and for release and addition of the Secondary Cells (SCells). In addition, the Conditional Handover (CHO) was proposed to enhance robustness so that the mobile device may receive the configuration of the target cell in advance (e.g., when the signal quality between the mobile device and the source cell is stable). The Dual Active Protocol Stack (DAPS) handover was proposed to reduce the interruption time since the mobile device can maintain two protocol stacks (e.g., one is associated with the source cell, and another one is associated with the target cell) for simultaneous connections with the source cell and the target cell during the handover. So far, the handover procedures, conditional handover, and DAPS handover may require complete Layer 2 (L2) reset and Layer 1 (L1) reset. The L2 may refer to the Medium Access Control (MAC) layer, Radio Link Control (RLC) layer, and Packet Data Convergence Protocol (PDCP) layer, and the L1 may refer to the Physical (PHY) layer. The complete L1 / L2 reset may result in longer latency, larger overhead, and longer interruption time than beam switch mobility. Thus, the L1 / L2 triggered mobility (LTM) may be designed to enable a serving cell change via L1 / L2 signaling, to reduce the latency, overhead, and interruption time during the handover procedures.

[0069] In addition, the LTM may allow the UE to perform early downlink and uplink synchronization to shorten the possible experience of interruption. For early downlink synchronization, the UE may activate the downlink beam of the candidate cell in advance. For early uplink synchronization, the UE may obtain the timing advance (TA) by itself or upon the reception of the cell switch command (CSC) to skip the lengthy random access (RA) procedure.

[0070] To exploit the extreme capacity brought from beamforming, a finer beam, which is sourced by CSI-RS, may be necessary. However, the LTM may only support the measurement of synchronization signal blocks (SSB) as a reference for the decision of early downlink (DL) beam activation. That is, after a cell switch, a UE may only use a SSB beam, instead of a CSI-RS beam, for data transmission. The UE may need to further go through a beam management procedure, including CSI-RS measurement and reporting, to obtain a CSI-RS beam. As a result, if such a procedure can be finished before the LTM cell switch, the UE may not experience the drop of data rate during the LTM execution as the current LTM mechanism.

[0071] To enable this, the UE may need to measure the CSI-RS of the candidate cells before the cell switch. However, the number of CSI-RSs of the candidate cells may be enormous and may cause large measurement overhead to the UE. To solve the problem, the present disclosure aims to enable the CSI-RS measurement for LTM while mitigating the measurement burden on the UE.

[0072] A network may include multiple cells, and a UE may or may not support the MR-DC configuration. That is, the UE may receive the service from at least two Radio Access Network (RAN) nodes (e.g., evolved node B (eNB), next generation node B (gNB)), e.g., a Master Node including Master Cell Group (MCG) and at least one Secondary Node (SN) including Secondary Cell Group (SCG), or the UE may receive the service from only one RAN node. The UE may be equipped with multiple receivers and transmitters, and it may be capable of supporting the MR-DC dedicated configurations. The network, having the information that the UE is capable of supporting MR-DC, may configure the UE with the MR-DC configuration (e.g., the SCG configuration), which is encapsulated in an RRC Reconfiguration message and is transmitted from the serving RAN node to the UE. In addition, the involved cells may belong to the same gNB distributed unit (gNB-DU) or different gNB-DUs. The involved gNB-DUs may belong to the same gNB centralized unit (gNB-CU) or different gNB-CUs.

[0073] LTM Preparation for CSI-RS Resources

[0074] In some implementations, the source node (e.g., the source gNB-CU, the source gNB-DU, or the source cell) may initiate an LTM preparation towards one or more candidate nodes (e.g., the candidate gNB-CUs, the candidate gNB-DUs, or the candidate cells). The initiation may include transmitting a first inter-node signaling (e.g., an inter-node RRC message or an XnAP message) by the source node to the one or more candidate nodes, where the first inter-node signaling may include one or more of the following (a)-(c).

[0075] (a) The information of measurement results reported by the UE.

[0076] (b) The identity of suggested candidate cells (e.g., the PhysCellId and / or PhysCellIdList).

[0077] (c) The indication indicating that the source node requests the support of dynamic LTM CSI-RS activation / deactivation (e.g., MAC CE-based LTM CSI-RS activation / deactivation or DCI-based LTM CSI-RS activation / deactivation).

[0078] In some implementations, the indication may take ENUMERATED format with value in {‘true’, ‘false’}. For example, a candidate node may consider that the source node supports the dynamic LTM CSI-RS activation / deactivation (e.g., the MAC CE-based LTM CSI-RS activation / deactivation or DCI-based LTM CSI-RS activation / deactivation) if the indication is present with value ‘true’. A candidate node may consider that the source node does not support the dynamic LTM CSI-RS activation / deactivation (e.g., MAC CE-based LTM CSI-RS activation / deactivation or DCI-based LTM CSI-RS activation / deactivation) if the indication is absent or is present with value ‘false’.

[0079] In some implementations, upon receiving the first inter-node signaling from the source node, a target node (or one of the one or more candidate nodes) may perform one or more of the following actions (a) and (b).

[0080] (a) The target node (or one of the one or more candidate nodes) may consider that the source node supports the dynamic LTM CSI-RS activation / deactivation based on the presence / absence and the value of the indication in the first inter-node signaling.

[0081] (b) The target node (or one of the one or more candidate nodes) may respond to the source node with a second inter-node signaling. The second inter-node signaling may include one or more of the following (i)-(iii).

[0082] (i) The information of candidate cells (e.g., the PhysCellId of the candidate cell and / or the RRCReconfiguration IE associated with the candidate cell).

[0083] (ii) The indication indicating whether the candidate node supports the dynamic LTM CSI-RS activation / deactivation.

[0084] In some implementations, the indication may take an ENUMERATED format with value in {‘true’, ‘false’} or an ENUMERATED format with value in {‘true’}. For example, the source node may consider that the candidate node supports the dynamic LTM CSI-RS activation / deactivation if the indication is present with value ‘true’ (e.g., the dynamic LTM CSI-RS activation / deactivation is applicable to all the candidate cells associated with the candidate node). The source node may consider that the candidate node does not support the dynamic LTM CSI-RS activation / deactivation if the indication is absent or is present with value ‘false’ (e.g., the dynamic LTM CSI-RS activation / deactivation is not applicable to all the candidate cells associated with the candidate node).

[0085] In some implementations, the indication may be a list of ENUMERATED formats with value {‘true’, ‘false’} or a list of ENUMERATED formats with value {‘true’}, where each of the ENUMERATED formats may be associated with a candidate cell associated with the candidate node and indicate whether the associated candidate cell supports the dynamic LTM CSI-RS activation / deactivation. For example, the source node may consider that the candidate cell supports the dynamic LTM CSI-RS activation / deactivation if the associated ENUMERATED format is present with value ‘true’. The source node may consider that the candidate cell does not support the dynamic LTM CSI-RS activation / deactivation if the associated ENUMERATED format is absent or is present with value ‘false’.

[0086] (iii) The CSI-RS resource configuration to be used for the LTM measurement. The CSI-RS resource configuration may be one or more (or a list of) information elements (IEs), where each of the IEs may indicate a CSI-RS resource.

[0087] In some implementations, upon receiving the second inter-node signaling from a candidate node, the source node may consider that the candidate node supports the dynamic LTM CSI-RS activation / deactivation based on the presence / absence and the value of the indication in the second inter-node signaling.

[0088] In some implementations, upon receiving the second inter-node signaling from a candidate node, the source node may consider that the candidate node supports the dynamic LTM CSI-RS activation / deactivation based on the presence / absence of the CSI-RS resource configuration in the second inter-node signaling.

[0089] The source node may consider that the candidate node supports the dynamic LTM CSI-RS activation / deactivation if the CSI-RS resource configuration is present in the second inter-node signaling. The source node may consider that the candidate node does not support dynamic LTM CSI-RS activation / deactivation if the CSI-RS resource configuration is absent from the second inter-node signaling.

[0090] In some implementations, for the source and the candidate nodes, if a first node considers that a second node supports the dynamic LTM CSI-RS activation, the first node may perform the procedure related to the LTM CSI-RS activation involving the second node.

[0091] The first node performing the procedure related to the LTM CSI-RS activation involving the second node may include that the first node may transmit signaling (e.g., the RRC message, MAC CE, and / or DCI) to activate the CSI-RS measurement configuration for LTM to the UE, where the CSI-RS measurement configuration for LTM may be associated with the second node. The first node performing the procedure related to the LTM CSI-RS activation involving the second node may include that the first node may initiate a coordination procedure (e.g., via XNAP protocols) towards the second node for the activation of aperiodic / semi-persistent CSI-RS transmission.

[0092] In some implementations, the UE may transmit first RRC signaling (e.g., an UECapabilityInformation message or an UEAssistanceInformation message) to the source node to provide the UE’s capability and / or preference for supporting LTM-related parameters, where the first RRC signaling may include one or more of the following (a)-(e). In some implementations, the UE may provide the UEAssistanceInformation only when the serving cell informs the UE that the serving cell supports the LTM operation (e.g., the serving cell may transmit the LTM-Config to the UE, and enable / disable the UE to transmit the UE information related to CSI-RS-based LTM measurement).

[0093] (a) An IE indicating the maximum number of total CSI-RSs that the UE supports for LTM measurement.

[0094] (b) An IE indicating the maximum number of CSI-RSs that the UE supports for LTM measurement for a candidate cell.

[0095] (c) An IE indicating the maximum number of total candidate cells that the UE supports for LTM measurement.

[0096] (d) An IE indicating the maximum number of the total inter-CU (e.g., inter gNB-CU) cells that the UE supports for LTM or the maximum number of cells per gNB-CU that the UE supports for LTM.

[0097] (e) An IE indicating the maximum number of the total inter-CU CSI-RSs that the UE supports for LTM or the maximum number of CSI-RSs per gNB-CU that the UE supports for LTM.

[0098] In some implementations, the source node may transmit second RRC signaling to the UE to provide the LTM-related information. In some implementations, the second RRC signaling may include the dynamic LTM CSI-RS configuration.

[0099] In some implementations, the CSI-RS resource set may not be associated with the SSB resource set. In some implementations, the second RRC signaling may configure a CSI-RS resource set or a CSI-RS resource set list to the UE without association with any SSB resource set. The second RRC signaling may include the LTM-CSI-ResourceConfig IE to indicate the CSI measurement resources for LTM. The LTM-CSI-ResourceConfig IE may include the LTM-CSI-ResourceConfigId IE for the UE to identify the CSI-RS resource set and an IE indicating the CSI-RS resource set (e.g., the LTM-CSI-CSIRS-ResourceSet IE). In some implementations, the UE may consider that the CSI-RS resource set is associated with the LTM-CSI-ResourceConfigId.

[0100] In some implementations, one or more CSI-RS resource sets may be associated with the SSB resource set. In some implementations, the second RRC signaling may configure one or more CSI-RS resource set, which may be associated with an SSB resource set, to the UE. The second RRC signaling may include the LTM-CSI-ResourceConfig IE to indicate the CSI measurement resources for LTM. The LTM-CSI-ResourceConfig IE may include the LTM-CSI-ResourceConfigId IE for the UE to identify the CSI resource sets for the LTM, the LTM-CSI-SSB-ResourceSet IE indicating the SSB resource set for the LTM CSI measurement, and one or more IEs indicating one or more CSI-RS resource sets (e.g., the LTM-CSI-CSIRS-ResourceSet IEs) for the LTM CSI measurement. In some implementations, the UE may consider that the one or more CSI-RS resource sets are associated with the LTM-CSI-ResourceConfigId, as well as associated with the SSB resource set.

[0101] In some implementations, a CSI-RS resource set for the LTM CSI measurement may be characterized / determined by an IE (e.g., the LTM-CSI-CSIRS-ResourceSet IE).

[0102] In some implementations, the generalized CSI-RS resource set for LTM CSI measurement may be characterized / determined by the IE. In some implementations, the IE may include one or more of the following (a)-(e).

[0103] (a) An IE indicating the ID of the CSI-RS resource set for the dynamic activation / deactivation for LTM measurement (e.g., the LTM-CSI-CSIRS-ResourceSetId IE). In some implementations, the IE may take an integer value, and the UE may associate the value with the CSI-RS set. In some implementations, the IE may be absent if only one CSI-RS resource set is associated with the LTM-CSI-ResourceConfigId. In some implementations, the IE may be present if more than one CSI-RS resource set is associated with the LTM-CSI-ResourceConfigId.

[0104] (b) An IE indicating the measurement type of the CSI-RS resource set for the dynamic activation / deactivation for LTM measurement. In some implementations, the IE may take an ENUMERATED format and may take values from {‘persistent’, ‘onDemand’, ‘conditional’}. For example, if the IE is ‘persistent’, the UE may consider that the UE starts measuring the CSI-RS upon the CSI-RS resource set is configured. For example, if the IE is ‘onDemand’, the UE may consider that the UE starts measuring the CSI-RS upon receiving activation signaling (e.g., an RRC message, a MAC CE, and / or DCI) from the source node. For example, if the IE is ‘conditional’, the UE may consider that the UE starts measuring the CSI-RS upon considering a preconfigured event to be satisfied. In some implementations, when ‘persistent’ is configured, additional signaling may be used to indicate whether to measure partial or total CSI resources associated with the CSI resource set. For example, an IE may take an ENUMERATED format and may take values from {‘partial’, ‘total’} to determine whether the additional signaling for activating partial CSI resources is needed to be monitored. In some implementations, the ‘conditional’ may be always configured when the conditional handover / LTM or event-triggered-based handover / LTM is applied.

[0105] (c) A first list of IEs indicating the CSI-RS resources for the dynamic activation / deactivation for LTM measurement. In some implementations, the IE may be an integer and indicate the identity of a CSI-RS resource configured for a candidate cell.

[0106] (d) A second list of IEs indicating the LTM candidate configurations. In some implementations, the IE may be an integer and indicate the identity of an LTM candidate configuration.

[0107] (e) An IE indicating the measurement condition for the conditional activation of CSI-RS resource set.

[0108] In some implementations, the number of the entries of the first list may equal the number of the entries of the second list. The UE may consider that the first entry of the first list is associated with the first entry of the second list, and the second entry of the first list is associated with the second entry of the second list, and so on. The UE may consider that the CSI-RS resource set for LTM measurement is associated with the CSI-RS resource whose identity equals the first entry of the first list and under the LTM candidate configuration whose identity equals the first entry of the second list, and associated with the CSI-RS resource whose identity equals the second entry of the first list and under the LTM candidate configuration whose identity equals the second entry of the second list, and so on.

[0109] In some implementations, the cell-specific CSI-RS resource set for LTM CSI measurement may be characterized / determined by the IE. In some implementations, the IE may include one or more of the following (a)-(e).

[0110] (a) An IE indicating the ID of the CSI-RS resource set for the dynamic activation / deactivation for LTM measurement (e.g., the LTM-CSI-CSIRS-ResourceSetId IE). In some implementations, the IE may take an integer value, and the UE may associate the value with the CSI-RS resource set.

[0111] (b) An IE indicating the measurement type of the CSI-RS resource set for the dynamic activation / deactivation for LTM measurement.

[0112] (c) An IE indicating the LTM candidate configuration (e.g., the LTM-CandidateId IE). In some implementations, the IE may take an integer value to associate the CSI-RS configuration with the LTM candidate configuration whose LTM-CandidateId IE has the same integer value.

[0113] (d) A list of IEs indicating the CSI-RS resources for the dynamic activation / deactivation for LTM measurement. In some implementations, the fourth IE may be an integer and indicate the identity of a CSI-RS resource configured for the candidate cell corresponding to the IE indicating the LTM candidate configuration.

[0114] (e) An IE indicating the measurement condition for the conditional activation of CSI-RS resource set.

[0115] In some implementations, the UE may consider that all the entries in the list are associated with the same candidate cell (e.g., associated with the same LTM candidate configuration). For example, the UE may consider that the CSI-RS resource set for LTM measurement is associated with the CSI-RS resources whose identity equals the entries in the list and under the LTM candidate configuration whose identity equals the IE indicating the LTM candidate configuration.

[0116] In some implementations, an IE indicating the measurement condition may be an event IE, where the event may include one or more of the following (a)-(e).

[0117] (a) CondEvent-L2: the quality of the serving beam becomes worse / lower than a threshold for a period, where the threshold and the period may be configured in the event IE.

[0118] (b) CondEvent-L3: the quality of a candidate beam becomes offset better than the serving beam for a period, where the offset and the period may be configured in the event IE.

[0119] (c) CondEvent-L4: the quality of a candidate beam becomes better / greater than a threshold for a period, where the threshold and the period may be configured in the event IE.

[0120] (d) CondEvent-L5: the quality of the serving beam becomes worse / lower than a first threshold and the quality of a candidate beam becomes better / greater than a second threshold for a period, where the first threshold, the second threshold, and the period may be configured in the event IE.

[0121] (e) CondEvent-UE: the decision is based on the UE.

[0122] The UE may consider a condition to be satisfied if the corresponding event in the event IE (e.g., at least one of CondEvent-L2 to CondEvent-L5) is met. For the event CondEvent-UE, the UE may consider the condition to be satisfied based on the UE’s implementations.

[0123] The quality may be the reference signal received power (RSRP) (e.g., L1-RSRP and / or L3-RSRP), reference signal received quality (RSRQ), or signal to interference plus noise ratio (SINR) of the measured SSB.

[0124] The candidate beam may be any of the SSB beams associated with the CSI-RS resource set containing the IE indicating the measurement condition.

[0125] The serving beam may be referred to as the SSB beam currently indicated by the source cell or the SSB beam with the best quality in the source cell.

[0126] The IE indicating the measurement condition may be present only if the IE indicating the measurement type is present with value ‘conditional’.

[0127] In some implementations, upon receiving the second RRC signaling from the source node, for each configured CSI-RS resource sets, the UE may perform one or more of the following actions (a)-(l).

[0128] (a) The UE may store the information included in an IE characterizing / determining the CSI-RS resource set.

[0129] (b) The UE may associate the CSI-RS resource set with the LTM-CSI-ResourceConfigId. The UE may associate the CSI-RS resource set with the LTM-CSI-ResourceConfigId if the CSI-RS resource set is the only one CSI-RS resource set included in the LTM-CSI-ResourceConfig IE. The UE may associate the CSI-RS resource set with the LTM-CSI-ResourceConfigId if the IE characterizing / determining the CSI-RS resource set does not include an ID to identify the CSI-RS resource set. In some implementations, the UE may identify the CSI-RS resource set by the CSI-ResourceConfigId.

[0130] (c) If an SSB resource set is present in the LTM-CSI-ResourceConfig IE, the UE may associate the CSI-RS resource set with the SSB resource set.

[0131] (d) The UE may associate the CSI-RS resource set with the ID included in the IE characterizing / determining the CSI-RS resource set. The UE may associate the CSI-RS resource set with the ID included in the IE characterizing / determining the CSI-RS resource set if the CSI-RS resource set is not the only one CSI-RS resource set included in the LTM-CSI-ResourceConfig IE. The UE may associate the CSI-RS resource set with the ID included in the IE characterizing / determining the CSI-RS resource set if the IE characterizing / determining the CSI-RS resource set includes an ID to identify the CSI-RS resource set. In some implementations, the UE may identify the CSI-RS resource set by both the CSI-ResourceConfigId and the ID included in the IE characterizing / determining the CSI-RS resource set.

[0132] (e) If there are two lists included in the IE characterizing / determining the CSI-RS resource set, with the first list including the NZP-CSI-RS-ResourceId IEs and the second list including LTM-CandidateId IEs, the UE may consider that the CSI-RS resource set for LTM measurement is associated with the CSI-RS resource whose identity equals the first entry of the first list and under the LTM candidate configuration whose identity equals the first entry of the second list, and associated with the CSI-RS resource whose identity equals the second entry of the first list and under the LTM candidate configuration whose identity equals the second entry of the second list, and so on.

[0133] (f) If the IE characterizing / determining the CSI-RS resource set includes a list of NZP-CSI-RS-ResourceId IEs and a single LTM-CandidateId IE, the UE may consider that the CSI-RS resource set for LTM measurement is associated with the CSI-RS resources whose identity equals the entries in the list and under the LTM candidate configuration whose identity equals the IE indicating the LTM candidate configuration.

[0134] (g) The UE may consider the measurement type of the CSI-RS resource set to be ‘persistent’. The UE may consider the measurement type of the CSI-RS resource set to be ‘persistent’ if the IE indicating the measurement type takes the value ‘persistent’. The UE may consider the measurement type of the CSI-RS resource set to be ‘persistent’ if the IE indicating the measurement type is absent from the IE characterizing / determining the CSI-RS resource set. The UE may consider the measurement type of the CSI-RS resource set to be ‘persistent’ if the IE indicating the measurement condition is absent.

[0135] (h) The UE may consider the measurement type of the CSI-RS resource set to be ‘on-demand’. The UE may consider the measurement type of the CSI-RS resource set to be ‘on-demand’ if the IE indicating the measurement type takes the value ‘on-demand’. The UE may consider the measurement type of the CSI-RS resource set to be ‘on-demand’ if the IE indicating the measurement type is absent from the IE characterizing / determining the CSI-RS resource set. The UE may consider the measurement type of the CSI-RS resource set to be ‘on-demand’ if the IE indicating the measurement condition is absent.

[0136] (i) The UE may consider the measurement type of the CSI-RS resource set to be ‘conditional’. The UE may consider the measurement type of the CSI-RS resource set to be ‘conditional’ if the IE indicating the measurement type takes the value ‘conditional’. The UE may consider the measurement type of the CSI-RS resource set to be ‘conditional’ if the IE indicating the measurement condition is present.

[0137] (j) The UE may consider the measurement type of the CSI-RS resource set to be ‘enable’ or ‘disable’. If the ‘enable’ is configured, the CSI-RS resource set may be always measured, but there may be additional signaling to indicate which one or more CSI resources associated with the CSI-RS resource set to be measured. If the ‘disable’ is configured, the CSI-RS resource set may not be measured. In some implementations, when the measurement for the CSI-RS resource set is disabled, the UE may measure the SSB only.

[0138] (k) If the IE indicating the measurement condition is present in the IE characterizing / determining the CSI-RS resource set, the UE may consider that the measurement condition is applied to all the beams associated with the SSB resource set associated with the CSI-RS resource set.

[0139] (l) If the IE indicating the measurement condition is present outside the IE characterizing / determining the CSI-RS resource set and inside the LTM-Config IE, the UE may consider that the measurement condition is applied to all the beams associated with the SSB resource set configured in the LTM-Config IE.

[0140] Persistent CSI-RS Beam Measurement

[0141] In some implementations, the UE may start performing the measurement on the CSI-RS resource associated with the CSI-RS resource set upon receiving the configuration of the CSI-RS resource set for LTM measurement. In some implementations, when a UE is configured with a CSI-RS resource set for LTM measurement, the UE may keep performing the measurement on the CSI-RS resources associated with the CSI-RS resource set.

[0142] The UE may start performing the measurement on the CSI-RS resource associated with the CSI-RS resource set upon receiving the configuration of the CSI-RS resource set for LTM measurement if the UE considers the measurement type of the CSI-RS resource set to be ‘persistent’. The UE may stop the measurement unless the corresponding CSI-RS configuration is released / suspend. The CSI-RS configuration may be released / suspended before and / or after the LTM execution.

[0143] The UE may stop the measurement based on dynamic signaling (e.g., the RRC message, MAC CE, or DCI) received from the source cell and / or the target cell.

[0144] In some implementations, the UE may receive a timer value associated with the CSI-RS resource set to be ‘persistent’. The UE may start a timer set to the timer value when the UE receives the associated CSI-RS resource configuration. When the timer expires, the UE may stop the measurement. When the UE stops the measurement before the timer expires, the UE may stop the timer. When the associated CSI-RS configuration is released, the UE may stop the timer.

[0145] On-Demand Activation of CSI-RS Beam Measurement

[0146] In some implementations, when a UE is configured with a CSI-RS resource set for LTM measurement, the UE may consider the CSI-RS resource set to be activated upon receiving first signaling from the source node. In some implementations, when a UE is configured with a CSI-RS resource set for LTM measurement and the CSI-RS resource set is considered to be activated, the UE may consider the CSI-RS resource set to be deactivated upon receiving second signaling from the source node. In some implementations, when a UE is configured with a CSI-RS resource set for LTM measurement and the CSI-RS resource set is considered to be activated, the UE may consider the CSI-RS resource set to be deactivated when / after the CSI-RS resource set is reported (e.g., the UE transmits the measurement report associated with the CSI-RS resource set). In some implementations, when a UE is configured with a CSI-RS resource set for LTM measurement and the CSI-RS resource set is considered to be activated, the UE may consider the CSI-RS resource set to be deactivated when / after the UE receives the (LTM) cell switch command. In some implementations, when a UE is configured with a CSI-RS resource set for LTM measurement and the CSI-RS resource set is considered to be activated, the UE may consider the CSI-RS resource set to be deactivated after a specific duration from the slot / symbol that receives the first signaling from the source node. In some implementations, the specific duration may be configured as a parameter in the LTM-related configuration (e.g., in the LTM-Config IE). In some implementations, when a UE is configured with a CSI-RS resource set for LTM measurement and the CSI-RS resource set is considered to be activated, the UE may consider the CSI-RS resource set to be deactivated when the UE receives another first signaling from the source node.

[0147] In some implementations, the first signaling or / and the second signaling may be received by the UE before the UE receives the candidate cell TCI states activation / deactivation MAC CE, and the source RS of the activated / deactivated TCI states may be the subset of CSI resources associated with the CSI-RS resource sets indicated in the first signaling / second signaling.

[0148] In some implementations, the first signaling or / and the second signaling may be received by the UE before the UE receives the cell switch command MAC CE, and the source RS of the activated / deactivated / indicated TCI states in the cell switch command (CSC) may be the subset of CSI resources associated with the CSI-RS resource sets indicated in the first / second signaling.

[0149] In some implementations, the signaling may be used to indicate the activation and the deactivation of the configured CSI resource sets / resources. Thus, the UE may consider the CSI-RS resource set or the CSI-RS resource to be activated upon receiving the signaling from the source node.

[0150] The UE may start performing the measurement on the CSI-RS resources associated with the CSI-RS resource set upon considering that the CSI-RS resource set is activated.

[0151] The UE may stop performing the measurement on the CSI-RS resources associated with the CSI-RS resource set upon considering that the CSI-RS resource set is deactivated.

[0152] The UE may start / stop performing the measurement on the CSI-RS resources associated with the CSI-RS resource set based on the first / second signaling from the source node if the UE considers the measurement type of the CSI-RS resource set to be ‘on-demand’.

[0153] In some implementations, the first signaling may be a MAC CE and / or DCI including one or more of the following fields (a) and (b).

[0154] (a) A first field indicating the ID of the LTM CSI resource configuration. In some implementations, the indicated ID may correspond to the LTM-CSI-ResourceConfigId associated with the CSI-RS resource set.

[0155] (b) A second field indicating the ID of the CSI-RS resource set. In some implementations, the indicated ID may correspond to the ID included in the IE characterizing / determining the CSI-RS resource set.

[0156] In some implementations, if the first signaling includes a first field and a second field, the UE may consider that the CSI-RS resource set, which is included in the LTM-CSI-ResourceConfigId indicated by the first field and whose ID is indicated by the second field, to be activated.

[0157] In some implementations, if the first signaling includes a first field and multiple second fields, the UE may consider that the CSI-RS resource sets, which are included in the LTM-CSI-ResourceConfigId indicated by the first field and whose IDs are indicated by the second fields, to be activated.

[0158] In some implementations, if the first signaling includes only a first field, the UE may consider that the CSI-RS resource set, which is included in the LTM-CSI-ResourceConfigId indicated by the first field, to be activated.

[0159] In some implementations, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the first field, the UE may consider all these CSI-RS resource sets to be activated.

[0160] In some implementations, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the first field, the UE may consider one of the CSI-RS resource sets / resources to be activated, where the one of the CSI-RS resource sets / resources may be the CSI-RS resource set / resource with the lowest / highest ID (e.g., the ID in the IE characterizing / determining the CSI-RS resource set / resource).

[0161] In some implementations, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the first field, the UE may ignore the first signaling.

[0162] In some implementations, if the first signaling includes multiple first fields and no second field, the UE may consider that the CSI-RS resource sets, which are included in the LTM-CSI-ResourceConfigId indicated by the first fields, to be activated.

[0163] In some implementations, for each first field, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the first field, the UE may consider all these CSI-RS resource sets to be activated.

[0164] In some implementations, for each first field, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the first field, the UE may consider one of the CSI-RS resource sets to be activated.

[0165] In some implementations, for each first field, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the first field, the UE may ignore this first field.

[0166] In some implementations, if the first signaling included multiple first fields and multiple second fields, for each first field, the UE may pair the first field with a second field. In some implementations, for each pair of first field and second field, the UE may consider that the CSI-RS resource set, which is included in the LTM-CSI-ResourceConfigId indicated by the first field and whose ID is indicated by the second field, to be activated.

[0167] In some implementations, the UE may not pair multiple first fields with the same second field. The UE may not pair multiple second fields with the same first field. In some implementations, in the first signaling, the number of first fields may equal the number of second fields. If the number is not equal, the UE may ignore the received signaling and may use UAI to reflect what the pairing situation. In some implementations, if the number of first fields does not equal the number of second fields, the UE may ignore the first signaling. In some implementations, the UE may pair the first (e.g., the frontmost) first field with the first (e.g., the first frontmost) second field, and pair the second (e.g., the second frontmost) first field with the second (e.g., the second frontmost) second field, and so on.

[0168] In some implementations, the second signaling may be a MAC CE and / or DCI including one or more of the following fields (a) and (b).

[0169] (a) A third field indicating the ID of the LTM CSI resource configuration. In some implementations, the indicated ID may correspond to the LTM-CSI-ResourceConfigId associated with the CSI-RS resource set.

[0170] (b) A fourth field indicating the ID of the CSI-RS resource set. In some implementations, the indicated ID may correspond to the ID included in the IE characterizing / determining the CSI-RS resource set.

[0171] In some implementations, if the second signaling includes a third and a fourth field, the UE may consider that the CSI-RS resource set, which is included in the LTM-CSI-ResourceConfigId indicated by the third field and whose ID is indicated by the fourth field, to be deactivated.

[0172] In some implementations, if the second signaling includes a third field and multiple fourth fields, the UE may consider that the CSI-RS resource sets, which are included in the LTM-CSI-ResourceConfigId indicated by the third field and whose IDs are indicated by the fourth fields, to be deactivated.

[0173] In some implementations, if the second signaling includes only a third field, the UE may consider that the CSI-RS resource set, which is included in the LTM-CSI-ResourceConfigId indicated by the third field, to be deactivated.

[0174] In some implementations, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the third field, the UE may consider all these CSI-RS resource sets to be deactivated. In some implementations, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the third field, the UE may consider one of the CSI-RS resource sets to be deactivated. In some implementations, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the third field, the UE may ignore the second signaling.

[0175] In some implementations, if the second signaling includes multiple third fields and no fourth field, the UE may consider that the CSI-RS resource sets, which are included in the LTM-CSI-ResourceConfigId indicated by the third fields, to be deactivated.

[0176] In some implementations, for each third field, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the third field, the UE may consider all these CSI-RS resource sets to be deactivated. In some implementations, for each third field, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the third field, the UE may consider one of the CSI-RS resource sets to be deactivated. In some implementations, for each third field, if there are more than one CSI-RS resource set included in the LTM-CSI-ResourceConfigId indicated by the third field, the UE may ignore this third field.

[0177] In some implementations, if the second signaling includes multiple third fields and multiple fourth fields, for each third field, the UE may pair the third field with a fourth field. In some implementations, for each pair of third field and fourth field, the UE may consider the CSI-RS resource set, which is included in the LTM-CSI-ResourceConfigId indicated by the third field and whose ID is indicated by the fourth field, to be deactivated.

[0178] In some implementations, the UE may not pair multiple third fields with the same fourth field. The UE may not pair multiple fourth fields with the same third field. In some implementations, in the second signaling, the number of third fields may equal the number of fourth fields. In some implementations, if the number of third fields does not equal the number of fourth fields, the UE may ignore the second signaling. In some implementations, the UE may pair the first (e.g., the frontmost) third field with the first (e.g., the first frontmost) fourth field, and pair the second (e.g., the second frontmost) third field with the second (e.g., the second frontmost) fourth field, and so on.

[0179] In some implementations, the signaling may include one or more fields to indicate the activation / deactivation status of the corresponding CSI-RS resource / CSI-RS resource set. The one or more fields may be set to 1 to indicate that the CSI-RS resource / CSI-RS resource set with ID i is activated and mapped to the codepoint of the DCI field. The one or more fields may be set to 0 to indicate that the CSI-RS resource / CSI-RS resource set with ID i is deactivated and mapped to the codepoint of the DCI field.

[0180] In some implementations, the UE may differentiate the first and the second signaling based on the associated RNTI. In some implementations, the UE may differentiate the first and the second signaling based on the MAC header (e.g., the LCID).

[0181] In some implementations, the first and the second signaling may be the same MAC CE and / or DCI and may include a fifth field in addition to those described above in the present disclosure. The fifth field may indicate whether this signaling is first signaling or second signaling (e.g., to activate CSI-RS resource sets or to deactivate CSI-RS resource sets). For example, the fifth field may include 1 bit. If the field is ‘1’, the UE may determine this signaling to be the first signaling (e.g., to activate CSI-RS resource sets). If the field is ‘0’, the UE may determine this signaling to be the second signaling (e.g., to deactivate CSI-RS resource sets).

[0182] In some implementations, the first and the second signaling may be the same MAC CE and / or DCI and the UE may consider the activation / deactivation based on the current state of the indicated CSI-RS resource set. The signaling may indicate a first set of CSI-RS resource sets, which may be currently activated CSI-RS resource sets, and / or a second set of CSI-RS resource sets, which may be currently deactivated CSI-RS resource sets. Upon receiving the signaling, the UE may deactivate the first set of CSI-RS resource sets and / or activate the second set of CSI-RS resource sets. In some implementations, if the indicated bit is “1”, it may mean the activation / deactivation change for the corresponding resource set. If the indicated bit is “0”, it may mean no change on the current activation / deactivation state for the corresponding set. In some implementations, the activation / deactivation may have time offset that UE will activate / deactivate the CSI-RS measurements after K slot when / upon receiving the signaling. The K value may be common for all candidate cells and based on UE capabilities. If the occasion of CSI-RS resource set is partially overlapped with the activation offset period, UE may start the CSI-RS measurement in next periodicity.

[0183] In some implementations, the maximum number of the activated CSI-RS resources associated with one CSI resource set may be based on a UE capability or be pre-defined in the 3GPP TS. In some implementations, the maximum number of activated CSI-RS resources associated “with one candidate cell” may also be determined based on UE capability or pre-defined in the 3GPP TS.

[0184] In some implementations, when one or more CSI-RS resource sets are activated, upon considering one or more new CSI-RS resource sets to be activated, the UE may perform one or more of the following actions (a)-(c). In some implementations, a CSI-RS resource set may be associated with one or more CSI report configurations.

[0185] (a) The UE may deactivate some of the one or more CSI-RS resource sets and keep the other one or more CSI-RS resource sets activated.

[0186] (b) The UE may deactivate some of the one or more CSI-RS resource sets and keep the other one or more CSI-RS resource sets activated based on the UE’s capability on maximum number of supported CSI-RS resource sets for LTM measurement. The UE may decide to deactivate N CSI-RS resource sets, where N equals the number of originally activated CSI-RS resource sets plus the number of newly activated CSI-RS resource sets minus the maximum number of supported CSI-RS resource sets for LTM measurement. The UE may decide to deactivate the CSI-RS resource sets with the N lowest / highest IDs (e.g., the ID included in the IE characterizing / determining the CSI-RS resource set).

[0187] (c) The UE may activate CSI-RS resource sets indicated in the first signaling and deactivate other CSI-RS resource sets. In other words, only activate CSI-RS resource sets indicated in the first signaling and / or deactivate CSI-RS resource sets other than CSI-RS resource sets indicated in the first signaling.

[0188] In some implementations, when a UE is not explicitly configured with a CSI-RS resource set for LTM measurement (e.g., the LTM-CSI-ResourceConfig IE does not include any CSI-RS-related configurations), upon receiving a third signaling, the UE may determine a CSI-RS resource set based on the third signaling. In some implementations, upon determining the CSI-RS resource set, the UE may consider the determined CSI-RS resource set to be activated. In some implementations, when a UE is considering a CSI-RS resource set to be activated, upon determining a new CSI-RS resource set, the UE may consider the new CSI-RS resource set to be activated, consider the original CSI-RS resource set to be deactivated, and dismiss the original CSI-RS resource set.

[0189] In some implementations, the third signaling may be a MAC CE and / or a DCI comprising one or more of the following fields (a) and (b).

[0190] (a) A first field indicating the ID of the LTM candidate configuration (e.g., the LTM-Candidate IE). In some implementations, the indicated ID may correspond to the LTM-CandidateId.

[0191] (b) A second field indicating the ID of the CSI-RS resource (e.g., the NZP-CSI-RS-Resource IE). In some implementations, the indicated ID may correspond to the NZP-CSI-RS-ResourceId.

[0192] In some implementations, if the third signaling includes a first field and a second field, the UE may determine that the CSI-RS resource set is associated with the CSI-RS resource which is included in the LTM-Candidate IE indicated by the first field and whose NZP-CSI-RS-ResourceId is indicated by the second field.

[0193] In some implementations, if the third signaling includes a first field and multiple second fields, the UE may determine that the CSI-RS resource set is associated with the CSI-RS resources which are included in the LTM-Candidate IE indicated by the first field and whose NZP-CSI-RS-ResourceId are indicated by the second fields.

[0194] In some implementations, if the third signaling includes one or more first fields and no second field, the UE may determine that the CSI-RS resource set is associated with the CSI-RS resources which are included in the LTM-Candidate IEs indicated by the one or more first fields.

[0195] In some implementations, if the third signaling includes multiple first fields and multiple second fields, for each first field, the UE may pair the first field with a second field. In some implementations, for each pair of first field and second field, the UE may determine that the CSI-RS resource set is associated with the CSI-RS resource which is included in the LTM-Candidate IE indicated by the first field and whose NZP-CSI-RS-ResourceId is indicated by the second field.

[0196] In some implementations, the UE may not pair multiple first fields with the same second field. The UE may not pair multiple second fields with the same first field. In some implementations, in the third signaling, the number of first fields may equal the number of second fields. In some implementations, if the number of first fields does not equal the number of second fields, the UE may ignore the third signaling. In some implementations, the UE may pair the first (e.g., the frontmost) first field with the first (e.g., the first frontmost) second field, and pair the second (e.g., the second frontmost) first field with the second (e.g., the second frontmost) second field, and so on.

[0197] Conditional Activation of CSI-RS Beam Measurement

[0198] In some implementations, when a UE is configured with a CSI-RS resource set for LTM measurement, the UE may consider the CSI-RS resource set to be activated upon considering the associated condition(s) to be satisfied. In some implementations, when a UE is configured with a CSI-RS resource set for LTM measurement and the CSI-RS resource set is considered to be activated, the UE may consider the CSI-RS resource set to be deactivated upon considering the associated condition to be not satisfied. In some implementations, the UE may perform the early timing advance (TA) acquisition (e.g., the PDCCH-order RA procedure, UE-based RA procedure, and / or UE-based TA measurement) towards the candidate cell upon the UE considers the CSI-RS resource set to be activated. In some implementations, the UE may perform the early DL synchronization based on the activated CSI resource. In other words, if there is only one CSI resource (or CSI resource set) ID to be measured when some conditions are met, the UE may consider that the beam quasi co-located (QCLed) with the measured CSI-RS resource is indicated.

[0199] The UE may start performing measurement on the CSI-RS resources associated with the CSI-RS resource set upon considering that the CSI-RS resource set is activated. The UE may stop performing measurement on the CSI-RS resources associated with the CSI-RS resource set upon considering that the CSI-RS resource set is deactivated. The UE may start / stop performing measurement on the CSI-RS resources associated with the CSI-RS resource set based on the evaluation of the condition associated with the CSI-RS resource set if the UE considers the measurement type of the CSI-RS resource set to be ‘conditional’.

[0200] The UE may associate a CSI-RS resource set with a condition in one or more of the following cases (a)-(d). The UE may associate a CSI-RS resource set with one or more conditions.

[0201] (a) The IE characterizing / determining the CSI-RS resource set and the IE characterizing / determining the condition are included in the same LTM-CSI-ResourceConfig IE.

[0202] (b) The IE characterizing / determining the CSI-RS resource set includes the IE characterizing / determining the condition.

[0203] (c) The IE characterizing / determining the condition is included in the LTM-Candidate IE including one or more CSI-RS resources associated with the CSI-RS resource set.

[0204] (d) The IE characterizing / determining the condition is included in the LTM-Config IE.

[0205] The UE may consider that a CSI-RS resource set is activated if the UE considers the condition(s) associated with the CSI-RS resource set to be satisfied, where considering a condition to be satisfied may include one or more of the following behaviors (a)-(e). The UE may consider the SSB beam currently indicated by the source cell to be the serving beam. The UE may consider the SSB beam currently with the best quality in the source cell to be the serving beam. The UE may consider the SSB beams associated with the CSI-RS resource set to be the candidate beams. The UE may consider the SSB beams associated with a candidate cell including the CSI-RS resource(s) associated with the CSI-RS resource set to be the candidate beams.

[0206] (a) The quality of the serving beam becomes worse / lower than a threshold for a period. In some implementations, the UE may determine the quality type (e.g., RSRP, RSRQ, SINR), the value of the threshold, and the value of the period based on the IE characterizing / determining the condition.

[0207] (b) The quality of a candidate beam becomes offset better / greater than the serving beam for a period. In some implementations, the UE may determine the quality type, the value of the offset, and the value of the period based on the IE characterizing / determining the condition.

[0208] (c) The quality of a candidate beam becomes better / greater than a threshold for a period. In some implementations, the UE may determine the quality type, the value of the threshold, and the value of the period based on the IE characterizing / determining the condition.

[0209] (d) The quality of the serving beam becomes worse / lower than a first threshold and the quality of a candidate beam becomes better / greater than a second threshold for a period. In some implementations, the UE may determine the quality type, the value of the first threshold, the value of the second threshold, and the value of the period based on the IE characterizing / determining the condition.

[0210] (e) Based on UE’s implementation to determine whether the condition is satisfied. In some implementations, the UE may consider that the conditional activation is based on the UE’s implementation while taking into account the candidate beam and / or the serving beam.

[0211] Network Node Coordination for On-Demand CSI-RS Measurement Activation

[0212] In some implementations, some coordination between the source node (e.g., the source gNB-DU) and the candidate node (e.g., the candidate gNB-DU) may be necessary for the on-demand activation of semi-persistent (SP) CSI-RS resources / resource sets.

[0213] In some implementations, during the LTM preparation stage (e.g., before the source node transmits a new RRCReconfiguration message including the LTM-Config IE to the UE), a candidate node may send an inter-node signaling (e.g., the second inter-node signaling described in the “LTM Preparation for CSI-RS Resources” Section) to the source node, where the inter-node signaling may include information related to SP CSI-RS resource set for LTM measurement purpose.

[0214] The information included in the inter-node signaling may be the aforementioned IEs described in the “LTM Preparation for CSI-RS Resources” Section, with the addition of an IE indicating a validity period. In some implementations, the validity period may be configured if the measurement type of the associated CSI-RS resource set is ‘on-demand’.

[0215] In some implementations, the validity period may represent the period when the UE and / or the source node may assume that a CSI-RS resource set is activated. In some implementations, the UE and / or the source node may assume that a CSI-RS resource set is deactivated outside the validity period. In some implementations, the source node may consider the starting point of the validity period to be the time when it receives the inter-node signaling including the validity period from the candidate node. In some implementations, the source node may consider the ending point of the validity period to be the time corresponding to the starting point of the validity period plus the value of the validity period.

[0216] In some implementations, the validity period may be configured on a per-cell basis; that is, the validity period is applicable to all the CSI-RS resources / CSI-RS resource sets associated with a candidate cell. For example, the source node may consider that the validity period is applicable to all the CSI-RS resources / CSI-RS resource sets associated with a candidate cell if the IE indicating the validity period is comprised in the LTM-Candidate IE corresponding to the candidate cell (and more specifically, configured outside any of the IEs characterizing CSI-RS sets).

[0217] In some implementations, the validity period may be configured on a per-CSI-RS-resource-set basis; that is, the validity period is applicable to a specific CSI-RS resource / CSI-RS resource set associated with a candidate cell. For example, the source node may consider that the validity period is applicable to a CSI-RS resource / CSI-RS resource set if the IE indicating the validity period is comprised in the IE characterizing the CSI-RS resource / CSI-RS resource set.

[0218] In some implementations, the source node may configure the UE with LTM-related configurations via RRC signaling (e.g., the second RRC signaling in the “LTM Preparation for CSI-RS Resources” Section). In some implementations, the RRC signaling may additionally comprise the validity period information.

[0219] In some implementations, the validity period may be configured if the measurement type of the associated CSI-RS resource set is ‘on-demand’. In some implementations, the validity period may be configured on a per-cell basis; that is, the validity period is applicable to all the CSI-RS resources / CSI-RS resource sets associated with a candidate cell. For example, the UE may consider that the validity period is applicable to all the CSI-RS resources / CSI-RS resource sets associated with a candidate cell if the IE indicating the validity period is comprised in the LTM-Candidate IE corresponding to the candidate cell (and more specifically, configured outside any of the IEs characterizing CSI-RS sets). In some implementations, the validity period may be configured on a per-CSI-RS-resource-set basis; that is, the validity period is applicable to a specific CSI-RS resource / CSI-RS resource set associated with a candidate cell. For example, the UE may consider that the validity period is applicable to a CSI-RS resource / CSI-RS resource set if the IE indicating the validity period is comprised in the IE characterizing the CSI-RS resource / CSI-RS resource set.

[0220] In some implementations, when applying the LTM-related RRC signaling (e.g., the second RRC signaling in the “LTM Preparation for CSI-RS Resources” Section), for each configured CSI-RS resource set, the UE may associate the CSI-RS resource set with a validity period.

[0221] In some implementations, the UE may associate the CSI-RS resource set with a validity period only if the CSI-RS resource set is an SP CSI-RS resource set. In some implementations, the UE may associate the CSI-RS resource set with a validity period if the IE indicating the validity period is comprised in the IE characterizing the CSI-RS resource set. In some implementations, the UE may associate the CSI-RS resource set with a validity period if the IE indicating the validity period and the IE characterizing the CSI-RS resource set are comprised in the same LTM-CSI-ResourceConfig IE. In some implementations, the UE may associate the CSI-RS resource set with a validity period if the IE indicating the validity period is comprised in the LTM-Candidate IE which comprises one or more CSI-RS resources associated with the CSI-RS resource set. In some implementations, the UE may associate the CSI-RS resource set with a validity period if the IE indicating the validity period is comprised in the LTM-Config IE.

[0222] In some implementations, the validity period may be determined in a real-time manner with the coordination between the source node (e.g., the source gNB-DU) and the candidate node (e.g., the candidate gNB-DU). More specifically, when the source node decides to activate one or more CSI-RS resource sets, the source node may send a first inter-node signaling to the candidate nodes which are associated with the one or more CSI-RS resource sets. In some implementations, the first inter-node signaling may comprise one or more of the following information (a)-(c).

[0223] (a) An indication indicating that the signaling is used for the activation of CSI-RS resource set activation.

[0224] (b) An indication of the CSI-RS resource set(s) to be activated. In some implementations, the indication may be one or more IDs (e.g., the ID included in the IE characterizing / determining the CSI-RS resource set, or the LTM-CSI-ResourceConfigId).

[0225] (c) A value of suggested validity period. In some implementations, the indication may take ENUMERATED value and correspond to a value of the suggested validity period.

[0226] In some implementations, upon receiving the first inter-node signaling from the source node, the candidate node may respond with the second inter-node signaling to the source node. In some implementations, the second inter-node signaling may include one or more of the following (a)-(d). The candidate node may determine the validity period based on the suggested validity period indicated in the first inter-node signaling.

[0227] (a) An indication of confirmation or rejection. In some implementations, the indication may take ENUMERATED format with value in {‘true’, ‘false’}. In some implementations, if the indication is present with value ‘true’, the source node may consider that the CSI-RS resource sets indicated in the first inter-node signaling are activated by the candidate node (e.g., the candidate node is going to transmit CSI-RSs on the CSI-RS resource sets). In some implementations, if the indication is absent or is present with value ‘false’, the source node may consider that the CSI-RS resource sets indicated in the first inter-node signaling are not activated by the candidate node (e.g., the candidate node is not going to transmit CSI-RSs on the CSI-RS resource sets).

[0228] (b) An indication of activated CSI-RS resource set(s). In some implementations, the indication may be one or more IDs (e.g., the ID included in the IE characterizing / determining the CSI-RS resource set, or the LTM-CSI-ResourceConfigId).

[0229] (c) An indication of starting offset. In some implementations, the indication may take ENUMERATED value and correspond to a value of starting offset. In some implementations, the source node may consider the starting offset to be the duration from receiving the second signaling to the candidate cell actually starting transmitting the CSI-RS on the activated CSI-RS resource set(s).

[0230] (d) An indication of validity period. In some implementations, the indication may take ENUMERATED value and correspond to a value of validity period. In some implementations, the indicated value of validity period may equal the indicated value of suggested validity period. In some implementations, the indicated value of validity period may not equal the indicated value of suggested validity period.

[0231] In some implementations, the validity period may be configured in the signaling activating the CSI-RS resource set (e.g., the first / third signaling described in the “On-Demand Activation of CSI-RS Beam Measurement” Section). In some implementations, the signaling may (in addition to the fields described in the “On-Demand Activation of CSI-RS Beam Measurement” Section) include one or more fields indicating the value of the validity periods.

[0232] In some implementations, if the signaling includes a single field indicating the value of the validity period and the signaling activates one or more CSI-RS resource sets, the UE may associate the one or more CSI-RS resource sets with the validity period indicated by the field.

[0233] In some implementations, if the signaling includes multiple fields indicating the value of the validity period and the signaling activates multiple CSI-RS resource sets, for each CSI-RS resource set, the UE may associate the CSI-RS resource set with a validity period indicated by one of the fields.

[0234] In some implementations, in the signaling, the number of fields indicating the value of the validity period may equal the number of the fields indicating the CSI-RS resource sets. In some implementations, if the number of fields indicating the value of the validity period and the number of fields indicating the CSI-RS resource sets are not equal, the UE may ignore the signaling or may ignore the fields indicating the CSI-RS resource sets. In some implementations, the UE may associate the first (e.g., the frontmost) indicated CSI-RS resource set with the first (e.g., the frontmost) field indicating the validity period and associate the second (e.g., the second frontmost) indicated CSI-RS resource set with the second (e.g., the second frontmost) field indicating the validity period, and so on.

[0235] In some implementations, the UE may initialize a validity timer associated with a CSI-RS resource set and start the validity timer upon considering that the CSI-RS resource set is activated and / or upon receiving the signaling activating the CSI-RS resource set (e.g., the first / third signaling described in the “On-Demand Activation of CSI-RS Beam Measurement” Section) from the source node. In some implementations, the UE may initialize the validity timer to the value corresponding to the validity period associated with the CSI-RS resource set. In some implementations, when the validity timer associated with a CSI-RS resource set expires, the UE may consider that the CSI-RS resource set is deactivated. In some implementations, the UE may stop a validity timer when the UE receives signaling deactivating the associated CSI-RS resource set (e.g., the second / fourth signaling described in the “On-Demand Activation of CSI-RS Beam Measurement” Section) from the source node. In some implementations, the UE may stop a validity timer upon the expiry of the validity timer. In some implementations, the UE may stop a validity timer when the UE releases the CSI-RS resource set. In some implementations, the UE may stop a validity timer when the UE executes / performs inter-CU LTM or when the UE receives LTM cell switch command. In some implementations, the UE may stop a validity timer when the UE is performing the LTM execution (e.g., upon receiving the cell switch command MAC CE).

[0236] In some implementations, the deactivation may be initiated by the candidate node. In some implementations, when a candidate cell is transmitting the CSI-RS on one or more CSI-RS resource sets for LTM measurement, the candidate node (e.g., the candidate gNB-DU) may send inter-node signaling to the source node (e.g., the source gNB-DU), where the inter-node signaling may include one or more of the following (a)-(c).

[0237] (a) An indication indicating that the inter-node signaling is used for the deactivation of CSI-RS resource set(s) for LTM measurement purposes.

[0238] (b) An indication of the CSI-RS resource set(s) to be deactivated. In some implementations, the indication may be one or more IDs (e.g., the ID included in the IE characterizing / determining the CSI-RS resource set, or the LTM-CSI-ResourceConfigId).

[0239] (c) An indication of the deactivation offset. In some implementations, the source node may consider the deactivation offset to be the duration from receiving the inter-node signaling to the candidate node stops transmitting CSI-RS on the CSI-RS resources associated with the deactivated CSI-RS resource set(s).

[0240] In some implementations, after the source node receives the inter-node signaling for deactivation from the candidate node, the source node may determine when to transmit the signaling to the UE to deactivate the CSI-RS resource sets.

[0241] In some implementations, the source node may determine the time to transmit the signaling to the UE based on the indication of deactivation offset included in the inter-node signaling received from the candidate node.

[0242] In some implementations, upon transmitting the signaling to the UE to deactivate the CSI-RS resource sets, the source node may transmit inter-node signaling to the candidate node to indicate the deactivation of measurement. In some implementations, upon receiving the inter-node signaling from the source node, the candidate node may stop transmitting CSI-RS on the deactivated CSI-RS resource set(s). The source node may transmit the inter-node signaling to the candidate node if the inter-node signaling received from the candidate node does not include the indication of deactivation offset.

[0243] In some implementations, the deactivation may be initiated by the source node. In some implementations, when the source node (e.g., the source gNB-DU) determines to deactivate CSI-RS resource set(s), the source node may send inter-node signaling to the candidate nodes associated with the deactivated CSI-RS resource sets after the source node transmits signaling to the UE to deactivate the CSI-RS resource sets. In some implementations, upon receiving the inter-node signaling from the source node, the candidate node may consider that the CSI-RS resource set(s) are deactivated and may stop transmitting CSI-RS on the CSI-RS resource sets.

[0244] In some implementations, the activation of the CSI-RS resource set for LTM measurement may only be applicable to the intra-CU LTM operation. The source node may only activate the CSI-RS resource sets associated with the cells which are associated with the same gNB-CU.

[0245] In some implementations, the signaling (e.g., the MAC CE and / or DCI) used to activate / deactivate one or more CSI-RS resource sets may also be the signaling to activate / trigger a conditional LTM. Specifically, upon receiving the MAC CE and / or the DCI described in the section “On-Demand Activation of CSI-RS Beam Measurement”, the UE may activate / deactivate the indicated CSI-RS resource sets; in the meanwhile, the UE may start evaluating the condition for performing the early TA acquisition and / or the condition for performing the conditional cell switch.

[0246] In some implementations, if the UE considers the condition(s) for performing the early TA acquisition to be satisfied, the UE may perform the early TA acquisition. In some implementations, the UE performing the early TA acquisition may include the UE performing the UE-based TA measurement for a candidate cell and / or the UE performing the RA-based TA acquisition before the UE performs the LTM execution.

[0247] In some implementations, if the UE considers the condition(s) for performing the conditional cell switch to be satisfied, the UE may perform the conditional cell switch. In some implementations, the UE performing the conditional cell switch may include the UE applying the RRCReconfiguration message included in the LTM-Candidate, using the configuration to connect to the target cell, and using the configuration to exchange data with the target cell.

[0248] In some implementations, for the same LTM candidate, the signaling (e.g., the MAC CE and / or DCI) used for activating / deactivating one or more CSI-RS resource sets associated with one LTM candidate may overwrite the previous signaling.

[0249] In some implementations, the activated CSI-RS resource sets for LTM measurement may be interrupted by L3 mobility event (e.g., the handover, CHO, CPA, CPC, CPAC). The UE may deactivate the activated CSI-RS resource sets during executing the L3 mobility. The UE may activate the CSI-RS resource sets upon completing the L3 mobility.

[0250] In some implementations, the activated CSI-RS resource sets for LTM measurement may be interrupted by the LTM operation (e.g., after receiving an LTM cell switch command MAC CE). However, the UE may re-activate the CSI-RS resource sets for the sub-sequent LTM operation.

[0251] In some implementations, for one (LTM candidate) cell, the activated CSI-RS resource sets for LTM measurement may or may not interrupt the (Layer-1 / Layer-3) SSB-based measurement associated with the same (LTM candidate) cell.

[0252] The activation / deactivation of CSI-RS resource sets may not be limited to the LTM case (e.g., the activation / deactivation of CSI-RS resource sets may be applied for other use cases where CSI-RS measurement is necessary (e.g., AI / ML, NES, etc.))

[0253] In some implementations, a UE may be configured with a CSI-RS resource set, which may be characterized / determined by an IE including an associated CSI-RS resource set ID and an associated SSB resource set (or an SSB beam set). The CSI-RS resource set may be associated with one or more CSI-RS resources configured under a candidate cell (e.g., the LTM-Candidate IE).

[0254] In some implementations, upon receiving a MAC CE that includes a field indicating a CSI-RS resource set ID and a field indicating a validity period, if the CSI-RS resource set ID indicated by the MAC CE is the CSI-RS resource set ID associated with the CSI-RS resource set, the UE may (a) consider that the CSI-RS resource set is activated and start performing measurement of the CSI-RS resources associated with the CSI-RS resource set, and (b) initialize the validity timer associated with the CSI-RS resource set to the value of the validity period indicated by the MAC CE and start the validity timer.

[0255] In some implementations, upon the validity timer expiry, the UE may consider that the CSI-RS resource set is deactivated and stop performing the measurement of the CSI-RS resources associated with the CSI-RS resource set.

[0256] FIG. 1 is a flowchart illustrating a method / process 100 performed by a UE for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM), according to an example implementation of the present disclosure.

[0257] In the action 102, the process 100 may start by receiving, from a base station (BS), a first CSI measurement configuration and a first CSI report configuration associated with the first CSI measurement configuration, where the first CSI measurement configuration may include a set of synchronization signal block (SSB) beams for LTM.

[0258] In the action 104, the process 100 may start to measure the set of SSB beams upon receiving the first CSI measurement configuration.

[0259] In the action 106, the process 100 may receive, from the BS, a second CSI measurement configuration, where the second CSI measurement configuration may include at least one set of CSI-RS beams for LTM, at least one CSI measurement configuration identifier (ID) associated with the at least one set of CSI-RS beams for LTM, and at least one condition associated with the at least one set of CSI-RS beams for LTM.

[0260] In the action 108, the process 100 may in response to receiving, from the BS, a medium access control (MAC) control element (CE) indicating one of the at least one CSI measurement configuration ID, start to measure one of the at least one set of CSI-RS beams, where the one of the at least one set of CSI-RS beams may be associated with the one of the at least one CSI measurement configuration ID.

[0261] In the action 110, the process 100 may in response to determining that one of the at least one condition is met, start to measure the one of the at least one set of CSI-RS beams, where the one of the at least one set of CSI-RS beams may be associated with the one of the at least one condition. The process 100 may then end.

[0262] In some implementations, the process 100 may store the first CSI measurement configuration upon receiving the first CSI measurement configuration, and store the second CSI measurement configuration upon receiving the second CSI measurement configuration.

[0263] In some implementations, the process 100 may receive, from the BS, a second CSI report configuration association with the second CSI measurement configuration, and transmit, to the BS, a report including a measurement result based on the second CSI report configuration after measuring the one of the at least one set of CSI-RS beams.

[0264] The steps / actions shown in FIG. 1 should not be construed as necessarily order dependent. The order in which the process is described is not intended to be construed as a limitation. Moreover, some of the actions shown in FIG. 1 may be omitted in some implementations and one or more actions shown in FIG. 1 may be combined.

[0265] The technical problem addressed by the method illustrated in FIG. 1 is how to efficiently activate and manage channel state information reference signal (CSI-RS) measurements in layer 1 / layer 2 triggered mobility (LTM) scenarios for a user equipment (UE), particularly by enabling selective triggering of finer-grained CSI-RS beam measurements only upon specific indications from the base station (BS) via a medium access control (MAC) control element (CE) or when predefined conditions are met, rather than requiring continuous or premature measurement of all potential beams, which could lead to excessive resource consumption, signaling overhead, and power drain in dynamic wireless environments. The advantageous technical effect achieved by the method illustrated in FIG. 1 is improved energy efficiency and reduced processing load on the UE by deferring CSI-RS measurements until explicitly triggered by a MAC CE identifying a specific configuration or until a relevant condition (such as signal quality thresholds or mobility events) is satisfied, thereby optimizing beam selection and handover performance in LTM while minimizing unnecessary transmissions and computations, enhancing overall network responsiveness and battery life in high-mobility 5G or beyond scenarios.

[0266] FIG. 2 is a flowchart illustrating a method / process 200 performed by a BS for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM), according to an example implementation of the present disclosure.

[0267] In the action 202, the process 200 may start by transmitting, to a user equipment (UE), a first CSI measurement configuration and a first CSI report configuration associated with the first CSI measurement configuration, where the first CSI measurement configuration may include a set of synchronization signal block (SSB) beams for LTM. The first CSI measurement configuration may cause the UE to start to measure the set of SSB beams upon receiving the first CSI measurement configuration.

[0268] In the action 204, the process 200 may transmit, to the UE, a second CSI measurement configuration, where the second CSI measurement configuration may include at least one set of CSI-RS beams for LTM, at least one CSI measurement configuration identifier (ID) associated with the at least one set of CSI-RS beams for LTM, and at least one condition associated with the at least one set of CSI-RS beams for LTM. The second CSI measurement configuration may cause the UE to in response to receiving, from the BS, a medium access control (MAC) control element (CE) indicating one of the at least one CSI measurement configuration ID, start to measure one of the at least one set of CSI-RS beams, and in response to determining that one of the at least one condition is met, start to measure the one of the at least one set of CSI-RS beams, where the one of the at least one set of CSI-RS beams may be associated with the one of the at least one CSI measurement configuration ID, and the one of the at least one set of CSI-RS beams may be associated with the one of the at least one condition. The process 200 may then end.

[0269] In some implementations, the first CSI measurement configuration may cause the UE to store the first CSI measurement configuration upon receiving the first CSI measurement configuration, and the second CSI measurement configuration may cause the UE to store the second CSI measurement configuration upon receiving the second CSI measurement configuration.

[0270] In some implementations, the process 200 may transmit, to the UE, a second CSI report configuration association with the second CSI measurement configuration, where the second CSI report configuration may cause the UE to transmit, to the BS, a report including a measurement result based on the second CSI report configuration after measuring the one of the at least one set of CSI-RS beams.

[0271] The steps / actions shown in FIG. 2 should not be construed as necessarily order dependent. The order in which the process is described is not intended to be construed as a limitation. Moreover, some of the actions shown in FIG. 2 may be omitted in some implementations and one or more actions shown in FIG. 2 may be combined.

[0272] The method illustrated in FIG. 2 is similar to that in FIG. 1, except that it is described from the perspective of the BS (instead of the UE).

[0273] FIG. 3 is a block diagram illustrating a node 300 for wireless communication in accordance with various aspects of the present disclosure. As illustrated in FIG. 3, a node 300 may include a transceiver 320, a processor 328, a memory 334, one or more presentation components 338, and at least one antenna 336. The node 300 may also include a radio frequency (RF) spectrum band module, a BS communications module, a network communications module, and a system communications management module, Input / Output (I / O) ports, I / O components, and a power supply (not illustrated in FIG. 3).

[0274] Each of the components may directly or indirectly communicate with each other over one or more buses 340. The node 300 may be a UE or a BS that performs various functions disclosed with reference to FIGS. 1 through 2.

[0275] The transceiver 320 has a transmitter 322 (e.g., transmitting / transmission circuitry) and a receiver 324 (e.g., receiving / reception circuitry) and may be configured to transmit and / or receive time and / or frequency resource partitioning information. The transceiver 320 may be configured to transmit in different types of subframes and slots including, but not limited to, usable, non-usable, and flexibly usable subframes and slot formats. The transceiver 320 may be configured to receive data and control channels.

[0276] The node 300 may include a variety of computer-readable media. Computer-readable media may be any available media that may be accessed by the node 300 and include volatile (and / or non-volatile) media and removable (and / or non-removable) media.

[0277] The computer-readable media may include computer-storage media and communication media. Computer-storage media may include both volatile (and / or non-volatile media), and removable (and / or non-removable) media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, Artificial Intelligence (AI) / Machine Learning (ML) module(s), or data.

[0278] Computer storage media may include RAM, DRAM, HBM, MRAM, FRAM, RRAM ROM, EEPROM, flash memory (or other memory technology), CD-ROM, Digital Versatile Disks (DVD) (or other optical disk storage), magnetic cassettes, magnetic tape, magnetic disk storage (or other magnetic storage devices), etc. Computer storage media may not include a propagated data signal. Communication media may typically embody computer-readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave, or other transport mechanism and include any information delivery media.

[0279] The term “modulated data signal” may mean a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. Communication media may include wired media, such as a wired network or direct-wired connection, and wireless media, such as acoustic, RF, infrared, and other wireless media. Combinations of any of the above listed components should also be included within the scope of computer-readable media.

[0280] The memory 334 may include computer-storage media in the form of volatile and / or non-volatile memory. The memory 334 may be removable, non-removable, or a combination thereof. Example memory may include solid-state memory, hard drives, optical-disc drives, etc. As illustrated in FIG. 3, the memory 334 may store a computer-readable and / or computer-executable instructions 332 (e.g., software codes and / or a set of instructions and / or AI / ML module(s)) that are configured to, when executed, cause the processor 328 to perform various functions disclosed herein, for example, with reference to FIGS. 1 through 2. Alternatively, the instructions 332 may not be directly executable by the processor 328 but may be configured to cause the node 300 (e.g., when compiled and executed) to perform various functions disclosed herein. The AI / ML module(s) may be implemented with a supervised learning approach or an unsupervised learning approach (e.g., Transductive approach and Inductive approach).

[0281] The processor 328 (e.g., having processing circuitry) may include an intelligent hardware device, e.g., a Central Processing Unit (CPU), a TPU, a GPU, a GPGPU, a microcontroller, an ASIC, etc. The processor 328 may include memory. The processor 328 may process the data 330 and the instructions 332 received from the memory 334, and information transmitted and received via the transceiver 320, the baseband communications module, and / or the network communications module. The processor 328 may also process information to send to the transceiver 320 for transmission via the antenna 336 to the network communications module for transmission to a CN.

[0282] One or more presentation components 338 may present data indications to a person or another device. Examples of presentation components 338 may include a display device, a speaker, a printing component, a vibrating component, etc.

[0283] In view of the present disclosure, it is obvious that various techniques may be used for implementing the disclosed concepts without departing from the scope of those concepts. Moreover, while the concepts have been disclosed with specific reference to certain implementations, a person of ordinary skill in the art may recognize that changes may be made in form and detail without departing from the scope of those concepts. As such, the disclosed implementations are to be considered in all respects as illustrative and not restrictive. It should also be understood that the present disclosure is not limited to the particular implementations disclosed and many rearrangements, modifications, and substitutions are possible without departing from the scope of the present disclosure.

Claims

1. A user equipment (UE) for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM), the UE comprising: 　　　　at least one processor; and 　　　　at least one non-transitory computer-readable medium coupled to the at least one processor and storing one or more computer-executable instructions that, when executed by the at least one processor, cause the UE to: 　　　　　　　　receive, from a base station (BS), a first CSI measurement configuration and a first CSI report configuration associated with the first CSI measurement configuration, the first CSI measurement configuration comprising a set of synchronization signal block (SSB) beams for LTM; 　　　　　　　　start to measure the set of SSB beams upon receiving the first CSI measurement configuration; 　　　　　　　　receive, from the BS, a second CSI measurement configuration, the second CSI measurement configuration comprising at least one set of CSI-RS beams for LTM, at least one CSI measurement configuration identifier (ID) associated with the at least one set of CSI-RS beams for LTM, and at least one condition associated with the at least one set of CSI-RS beams for LTM; 　　　　　　　　in response to receiving, from the BS, a medium access control (MAC) control element (CE) indicating one of the at least one CSI measurement configuration ID, start to measure one of the at least one set of CSI-RS beams, the one of the at least one set of CSI-RS beams being associated with the one of the at least one CSI measurement configuration ID; and 　　　　　　　　in response to determining that one of the at least one condition is met, start to measure the one of the at least one set of CSI-RS beams, the one of the at least one set of CSI-RS beams being associated with the one of the at least one condition.

2. The UE of claim 1, wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to: 　　　　store the first CSI measurement configuration upon receiving the first CSI measurement configuration; and 　　　　store the second CSI measurement configuration upon receiving the second CSI measurement configuration.

3. The UE of claim 1, wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the UE to: 　　　　receive, from the BS, a second CSI report configuration association with the second CSI measurement configuration; and 　　　　transmit, to the BS, a report including a measurement result based on the second CSI report configuration after measuring the one of the at least one set of CSI-RS beams.

4. A method performed by a user equipment (UE) for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM), the method comprising: 　　　　receiving, from a base station (BS), a first CSI measurement configuration and a first CSI report configuration associated with the first CSI measurement configuration, the first CSI measurement configuration comprising a set of synchronization signal block (SSB) beams for LTM; 　　　　starting to measure the set of SSB beams upon receiving the first CSI measurement configuration; 　　　　receiving, from the BS, a second CSI measurement configuration, the second CSI measurement configuration comprising at least one set of CSI-RS beams for LTM, at least one CSI measurement configuration identifier (ID) associated with the at least one set of CSI-RS beams for LTM, and at least one condition associated with the at least one set of CSI-RS beams for LTM; 　　　　in response to receiving, from the BS, a medium access control (MAC) control element (CE) indicating one of the at least one CSI measurement configuration ID, starting to measure one of the at least one set of CSI-RS beams, the one of the at least one set of CSI-RS beams being associated with the one of the at least one CSI measurement configuration ID; and 　　　　in response to determining that one of the at least one condition is met, starting to measure the one of the at least one set of CSI-RS beams, the one of the at least one set of CSI-RS beams being associated with the one of the at least one condition.

5. A base station (BS) for activation of channel state information (CSI)-reference signal (RS) measurements in layer 1 (L1) / layer 2 (L2) triggered mobility (LTM), the BS comprising: 　　　　at least one processor; and 　　　　at least one non-transitory computer-readable medium coupled to the at least one processor and storing one or more computer-executable instructions that, when executed by the at least one processor, cause the BS to: 　　　　　　　　transmit, to a user equipment (UE), a first CSI measurement configuration and a first CSI report configuration associated with the first CSI measurement configuration, the first CSI measurement configuration comprising a set of synchronization signal block (SSB) beams for LTM; and 　　　　　　　　transmit, to the UE, a second CSI measurement configuration, the second CSI measurement configuration comprising at least one set of CSI-RS beams for LTM, at least one CSI measurement configuration identifier (ID) associated with the at least one set of CSI-RS beams for LTM, and at least one condition associated with the at least one set of CSI-RS beams for LTM, wherein: 　　　　　　　　　　　　the first CSI measurement configuration causes the UE to: 　　　　　　　　　　　　　　　　start to measure the set of SSB beams upon receiving the first CSI measurement configuration; and 　　　　　　　　　　　　the second CSI measurement configuration causes the UE to: 　　　　　　　　　　　　　　　　in response to receiving, from the BS, a medium access control (MAC) control element (CE) indicating one of the at least one CSI measurement configuration ID, start to measure one of the at least one set of CSI-RS beams, the one of the at least one set of CSI-RS beams being associated with the one of the at least one CSI measurement configuration ID; and 　　　　　　　　　　　　　　　　in response to determining that one of the at least one condition is met, start to measure the one of the at least one set of CSI-RS beams, the one of the at least one set of CSI-RS beams being associated with the one of the at least one condition.

6. The BS of claim 5, wherein: 　　　　the first CSI measurement configuration further causes the UE to: 　　　　　　　　store the first CSI measurement configuration upon receiving the first CSI measurement configuration; and 　　　　the second CSI measurement configuration further causes the UE to: 　　　　　　　　store the second CSI measurement configuration upon receiving the second CSI measurement configuration.

7. The BS of claim 5, wherein the one or more computer-executable instructions, when executed by the at least one processor, further cause the BS to: 　　　　transmit, to the UE, a second CSI report configuration association with the second CSI measurement configuration, wherein the second CSI report configuration causes the UE to: 　　　　　　　　transmit, to the BS, a report including a measurement result based on the second CSI report configuration after measuring the one of the at least one set of CSI-RS beams.

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